ISTANBUL, Nov 22 (Reuters) – Prominent Turkish journalists went on trial accused of links to a shadowy group seeking to topple the government, in a case that has fuelled Western concern over media freedom in Prime Minister Tayyip Erdogan’s Turkey.

Gathered outside the courthouse on Tuesday, supporters of journalists Nedim Sener and Ahmet Sik bore a large banner with the message: “There can be no free society without free journalism.”

Members of a journalist union dressed in white with a picture of man holding a hand over his mouth to symbolise the silencing of a critical press.

As part of a long struggle with EU candidate Turkey’s secularist old guard, Erdogan, riding a wave of popularity and economic success, has cut back the power of generals who removed several governments in the latter half of the 20th Century.

Hundreds of people, including senior serving and retired officers, as well as journalists and academics, have been arrested in connection with an alleged ‘Ergenekon’ plot to carry out bombings and assassinations to trigger a military takeover.

Thirteen defendants, including Sener and Sik, went on trial on Tuesday, having been first detained in March, just three months before Erdogan won a third term in a national election. A fourteenth defendant died in prison earlier this month.

Among the charges listed on the indictment are membership of an armed terrorist group and stirring hatred.

Often held up as a model Muslim democracy for countries emerging from the Arab Spring, Erdogan’s government has faced repeated accusations of trying to tame the media and smother opposition since coming to power in 2002.

Sik had been tried once over a book he co-wrote about Ergenekon. Detaining Sik again in March, police attempted to confiscate copies of an unpublished book in which he raised old allegations of links between the police and a moderate Islamic movement said to have influence in the ruling AK Party.

The Gulenist movement is led by Fethullah Gulen, an Islamic preacher who left Turkey for the United States after the military forced an Islamist-led coalition to quit power in 1997.

“The draft of Ahmet Sik’s book is not a bomb,” Johann Bihr, of Reporters Sans Frontieres, told Reuters at the courthouse.

“This is a funny and tragic parody. There’s no way we can talk about impartial justice here.”

Sener has written books about the investigation into the killing of Turkish-Armenian journalist Hrant Dink in 2007.

Held under anti-terrorism laws that allow for lengthy pre- trial detention, the journalists had a petition for release rejected before the Istanbul court adjourned until Dec. 26, leaving a higher court to decide on another petition for a presiding judge to be changed.

Despite Erdogan’s declarations of respect for the republic’s secular traditions, foes say his AK Party has a hidden Islamist agenda.

Various international journalism bodies were among observers at Tuesday’s court hearing.

“Press freedom is the thermometer of democracy. You can’t have full democracy without a free press,” European Federation of Journalists vice-president Philippe Leruth told Reuters before the hearing.

Turkish media groups say nearly 70 journalists are in jail. The government says they are there because of non-journalistic activities, not because of what they wrote.

Due to the proliferation of cases, Turkey has fallen to 138th out of 178 countries reviewed for the World Press Freedom Index by Reporters without Borders, a media freedom pressure group, from 101st in 2007. (Writing by Daren Butler and Simon Cameron-Moore)